Simple Urine Test Diagnoses Prostate Cancer

Scientists at the University of Surrey, (Guildford, UK), tested 194 urine samples for the presence of a protein called Engrailed-2 (EN-2), between June 2007 to June 2010. Included in the study participants were men with lower urinary tract symptoms, individuals concerned they may have an asymptomatic prostate cancer, for instance having a positive family history, and men with an abnormal prostate specific antigen (PSA) test. Two groups of controls were also tested. Samples were assayed using an in house enzyme-linked immunoassay (ELISA) that used two mouse monoclonal antibodies. Other studies were conducted to detect the presence of EN-2 included Western blot, and semiquantative polymerase chain reactions (RT-PCR).

The stability of En-2 protein in urine was shown to be at least four days at room temperature, allowing postal collection of some samples. EN2 protein was detected in 54 of the 82 (66%) men with prostate cancer confirmed by biopsy, using a cutoff point of 42.5 µg/L, and in nine men in this EN2 positive group, their PSA was less than 2.5 ng/mL. The authors reported that using the 42.5 ng/mL cut off point, the EN2 test has a sensitivity of 66% and a specificity of almost 90%. The potential utility of EN2 as a prostate cancer biomarker was demonstrated by its presence in the urine of men with low PSA of less than 2.5 µg/L, but histologically confirmed prostate cancer on biopsy.

The ELISA based assay for EN-2 will potentially allow a number of different detection platforms including a lateral flow application with a "dip stick” test, which could be performed quickly and cheaply in primary care or as a component of a large-scale screening program. EN2 is an important protein in the development of the human embryo and, like many similar fetal proteins, its production is switched off at birth. However, this study showed that EN2 is switched back on again in prostate cancer.

Hardev Pandha, MD, PhD, professor of oncology at the university, said, "In this study we showed that the new test was twice as good at finding prostate cancer as the standard PSA test. Only rarely did we find EN2 in the urine of men who were cancer free, so if we find EN2 we can be reasonably sure that a man has prostate cancer. EN2 was not detected in men with noncancer disorders of the prostate such as prostatitis or benign enlargement." The study was published on March 1, 2011, in the journal Clinical Cancer Research.

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